In the production of small batteries, selected samples of the products are typically tested at various stages in the manufacturing process for quality control. In fact, in certain critical applications, it may be necessary to test every battery made in a manufacturing facility.
Some battery manufacturing plants manufacture batteries in several sizes, such as D cell, AA cell, or other sizes. In any of these cell sizes, the battery is constructed with an elongate cylindrical body with positive and negative terminals at the opposite ends of the body. These types of cells, however, differ in diameter and thickness. The terminal spacing will vary with length. Further, even within manufacturing tolerances, the shape and contour of the terminals may vary enough to present difficulty in making a minimum resistance contact with the terminals.
A battery contact assembly was shown and described in my earlier U.S. Pat. No. 5,903,154. The assembly of the '154 patent enabled a single test assembly to accommodate batteries over a wide range of sizes and shapes. Positive and negative contact terminals were deployed opposite one another and were positioned to clamp against the positive and negative terminals at the ends of the batteries, without regard to the length of the cylindrical battery. For testing, it is necessary to connect to the battery terminals with a high quality, low resistance connection. The quality of the connection is normally assured by controlling the spring force of the spring which forces the battery contact against the terminal. Should the contact force be outside a desired range, false readings may be obtained because the contact is not sufficient to enable full current flow between the battery terminal and the battery contact.
The contact assembly of the '154 patent provided appropriate contact to the battery through the use of a movable contact. That movable contact came into abutting contact with the battery terminal at a plurality of tines or prongs. For most low current applications, the tine contact structure provides adequate contact between the terminal and the contact. For high current applications, however, such as for example 100 amps or higher, such a contact presents a high resistance to current flow between the terminal and the contact, resulting in high temperatures. The high temperatures can damage the battery terminal under test, and can even weld the contact to the terminal. Furthermore, the tines or prongs of the contact did not accommodate the variations in the shape or contour of the terminals, and the contact was thus not self-adjusting.
Thus, there remains a need for a simple, robust, effective contact to minimize the electrical resistance at the point of contact between a battery terminal and a contact. The contact should provide an easy to use contact for a testing assembly, but should also be adaptable to other applications. The contact disclosed herein solves these and other needs in the art.